This also includes C#7’s new inline out variables, so this does the try-parse, conversion to the explicit enum type and initialises+populates the myStatus variable. Because a single quote is used for indicating the start and end of a string; you need to escape it. Note, as explained in the most upvoted answer, this replaces values in the column. You need to add an UPDATE statement at first with the full address of all tables to join with, and then add the SET statement.

That ConversionService will be picked up by Spring and then used whenever a type conversion needs to be performed by the framework. … If no ConversionService is registered with Spring, the original PropertyEditor-based system is used. As I understand, an alternative of doing this is to have it in the Spring config file, and load it as a bean reference (correct me if I’m wrong), i.e.

It will also give you the bit-type columns, and it works at least in MS Sql Server. A very simple answer if you say you don’t care which address is used. By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy. The blogpost is Enums – Better syntax, improved performance and TryParse in NET 3.5. If the default value is not an enum the Enum.TryParse would fail and throw an exception which is catched.

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• The blacklist_users table also has a «has_run» indicator which needs to be set to 1 (true) when it has been run so it can be skipped in future queries.
• For this table it should return all rows except the 3rd (or 1st – any of those two addresses are okay but only one can be returned).
• So if you have a WHERE clause here, internally, the results are getting brought back in the join and then the WHERE clause is being queried against that dataset.
• Here is the same with an example for better understanding.
• The string values can then be concatenated together with a concatenate operator.

Therefore, this is the most optimal query to avoid needless lookups of the users table… So if you have a WHERE clause here, internally, the results are getting brought back in the join and then the WHERE clause is being queried against that dataset. Instead, we can move all the where clause conditions into the join, and internally, remove the second query completely.

how do I query sql for a latest record date for each user

And so on.So this is an easy way of passing the value to another page (with select option list) through GET in url. Inner Query will return the latest date for the current user, Outer query will pull all the data according to the inner query result. It might not work so well on large tables, even with good indexing. Performance seems to be ok however it requires a bit of boilerplate code setup. I used class (strongly-typed version of Enum with parsing and performance improvements). I found it on GitHub, and it should work for .NET 3.5 too.

Your Answer

But you can achieve this in just one line.Please try following declaration and you will get all the comma separated values in a String list. This uses a common table expression (CTE) to assign a unique rn (row number) to each record for each user, based on the user_id and sorted in descending order by date. The final query then selects only the records with rn equal to 1, which represents the most recent record for each user.

I would not want to experience the consequences of users, willingly or unwillingly, triggering this behavior. For me this was preferable because I didn’t need to «try» to parse and I also want the result inline without generating an output variable. And also you need to have the following line defined in your xml configuration.

(Excel) Conditional Formatting based on Adjacent Cell Value

• In eduffy’s answer, the accent symbol is (presumably accidentally) placed as the delimiter for the string instead of replacing the apostrophe in O’Brian.
• Even if you added an order by to the end of your query, it would preserve the ordering in the over command when numbering.
• The final query then selects only the records with rn equal to 1, which represents the most recent record for each user.
• I used this way to take the last record for each user that I have on my table.

It was a query to get last location for salesman as per recent time detected on PDA devices. To get the latest record date along with the corresponding value for each user, you can use a subquery or a common table expression (CTE) in SQL. This is similar to one of the answers above, but in my opinion it is a lot simpler and tidier. The sub-query makes sure to find only rows of the latest date, and the outer GROUP BY will take care of ties. When there are two entries for the same date for the same user, it will return the one with the highest value. Additionally, as mentioned by others, performance is less than ideal for large enums, namely linear in the number of possible values.

Query

The blacklist_users table also has a «has_run» indicator which needs to be set to 1 (true) when it has been run so it can be skipped in future queries. Another advantage is that the syntax used is very simple, and that the meaning of the query is rather easy to grasp (take all rows such that no newer row exists for the username being considered). Connect and share knowledge within a single location that is structured and easy to search. In this sample you can send every string, and set your Enum.

With these two, it even handles all the redundant whitespaces including newline, so you don’t need to add additional logics to trim them. I like it because if the conditional logic gets more complex you can move it to a function and just pass in that function instead of the lambda. You can see list contain method implementation, to understand why it works. Here is the same with an example for better understanding. But this checks the whole dataframe just to get one value, so I imagine it’s wasteful.

The short answer is to use two single quotes – » – in order for an SQL database to store the value as ‘. In the table, one customer like John Smith can have multiple addresses.I need the SELECT query for this table to return only first row found where there are duplicates in ‘CName’. For this table it should return all rows except the 3rd (or 1st – any of those two addresses are okay but only one can be returned). And using CollectionUtils.addAll(myList, myString), you can get the list of strings. The solution provided is not working fine, since it ads the string with two single quote in database, the simplest way is to use anti back slash before the apostrophe (single quote).

The apostrophe character can be inserted by calling the value reporting form CHAR function with the apostrophe’s ASCII table lookup value, 39. The string values can then be concatenated together with a concatenate operator. You want to check for »», and replace them if they exist in the string with »»» in order to escape the lone single quote. However, by giving it more conditions it can «skip» every row we’re not updating.

All the conditions are in one place and the rows to update are in another place. You then have a table of users to disable (blacklist) at one go because you find out they’ve all done something bad. You’ll get the best performance if you forget the where clause and place all conditions in the ON expression.

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It has some memory overhead since it buffers a dictionary. If you are using Spring Boot 2, it works as is, without any additional configuration. In a Spring application, you typically configure a ConversionService instance per Spring container (or ApplicationContext).

This one should give you the correct result for your edited question. I see most of the developers use an inline query without considering its impact on huge data. From my experience the fastest way is to take each row for which there is no newer row in the table. I have a table that is a collection entries as to when a user was logged on.